The invention relates to an audio-visual reproduction device for transmitted light recordings of picture, audio and control signals, which associated with each other directly in a certain order on a spiral are provided on a disc-shaped information vehicle adapted to be turned about the center point of the spiral at an even speed of performance, and adjacent to the information vehicle there is an arrangement, adapted to move in the direction radial with respect to the spiral on lead screws in synchronism with the playback of the information vehicle, the arrangement comprising on one side of the information vehicle an illuminating device and on the other side an optical sensing device for the picture, audio and control signals and furthermore means are provided by means of which the signals originating from the information vehicle are converted into electric pulses, which can be processed by a TV receiver, and displacements of the information vehicle in the direction perpendicular to its plane are compensated for on the basis of optical signals in order to keep in focus an objective for the picture signals and these optical signals can be derived from a signal track of the information vehicle and they change in accordance with its displacement perpendicular to its plane.
Such reproducing devices can be used for the playback of optical information vehicle discs with spirally arranged moving picture and audio recordings and their representation by means of a TV set. In this case the picture recordings are direct images, which can be reduced in size as far as the limit of resolution of the image vehicle layer employed, for example down to a size of 2 square millimeters in area, and it is not necessary to convert the images into linear signals for the information vehicle. The images therefore retain their complete two-dimensionally arranged information content and as a result require a smaller overall area. The optical storage of the overall information content therefore makes possible in a simple manner a duplication of the information vehicle photographically or by a printing process. Such reproducing devices are furthermore suitable for the reproduction of selected individual images and can therefore be used as an information memory, from which individual pieces of information can be read out.
The German specification (Offenlegungsschrift) 2,121,379 describes such a reproducing device in the case of which an objective, adapted to follow the perpendicular displacements of the information vehicle is provided and which serves for reading out the picture information. The control of the objective is ensured by photo-electric sensors, which register the changes due to the vertical movements of the disc, in the optical control signals supplied to the sensors and the latter regulate the excitation of magnets, which bring the objective into focus in each case as required. However the compensation for changes in the audio and control signals as a consequence of perpendicular displacements of the information vehicle disc is neglected and there is furthermore as a whole no compensation or displacements of the information vehicle in its radial plane, which are to be mechanically suppressed.
For the conversion of the optical signals into electrical ones a TV camera is provided, which more especially as regards color reproduction brings about substantial losses of information from the information content of the information vehicle employed. The use of a TV camera furthermore means that the picture frequency on playback of the information vehicle must be adapted to the frequency of the TV set driven by the TV camera. For switching over from one image to the next one any conversion of the moving image into a still image viewed by the TV camera the German specification proposes the use of a rotary prism, that is to say a mechanical component which will be subject to wear and is not free of mechanical displacements or misalignments.